1. Field of the Invention
This invention relates generally to vehicle control systems and more particularly to a dual axis carriage assembly for a control handle employed in the operation of industrial load handling equipment.
2. Related History
Industrial load handling equipment such as fork lifts and the like, required precise and exact control systems for safety and efficiency. Equipment of this type often operated in tight quarters such as between isles in high bay storage racks and also inside semi-trailers. Further, the weight of a typical electric motor driven lift truck with batteries ranged from between 9,000 pounds unloaded to 16,000 loaded. The direction of travel, speed, load position, tilt angle and load engagement, as controlled by a vehicle operator, were crucial safety and operational parameters.
Many operator control functions were integrated into a single control handle wherein the pivotal movement of the handle about one axis controlled vehicle travel direction and speed, for example, while the movement of the handle about a transverse axis controlled a different function, such as the elevation of lift forks.
It was also desireable to have both axes of control movement intersect at a single pivot point and to have control signals generated as a direct function of the angular position of the handle along both axes.
While x-y movement control systems such as joy sticks have been heretofore incorporated in applications such as personal computers and games, the implementation of joy stick type controls in an industrial work place environment, such as the operating floor of a plant or warehouse, by hourly laborers, rather than engineers or technicians, presented unique challenges.
For example, an operator riding with and controlling a fork lift would often resort to excessive force and sudden control handle movements, which was compounded by the fact that the operators frequently wore work gloves. Joy stick controls did not have the structural durability to withstand the shock and control forces generated by such applications.